Heidelberg 2015 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 31: Poster: Quantum Optics and Photonics II

Q 31.48: Poster

Dienstag, 24. März 2015, 17:00–19:00, C/Foyer

Engineering adiabaticity with optimal control — •Lukas S. Theis¹, Tobias Chasseur¹, Daniel J. Egger¹, and Frank K. Wilhelm^1,2 — ¹Universität des Saarlandes, Saarbrücken, Germany — ²IQC and Dept. of Physics and Astronomy, University of Waterloo, Canada

In this work the time evolution of a system modelled by Landau-Zener (LZ) physics is studied using numerical optimal control methods. Within the framework of superconducting qubits one makes use of avoided crossings, governed by LZ physics, to realize entangling gates that are crucial for quantum computation. In particular adiabatic time evolution, i.e. staying in the same energy branch all the time, is the basis of many proposals for quantum computing schemes.

This work addresses one of many possible examples for such a time evolution: adiabatic population transfer between two bare states, such as a qubit and a resonator. The numerical results reveal the possibility to preserve adiabaticity at limiting time, finding a non-uniform quantum speed limit. Additionally, an analytical approach using the Magnus expansion is presented, which explains the observed pulse shapes.